Posttranslational control of membrane-skeleton (ankyrin and alpha beta- spectrin) assembly in early myogenesis

Adult chicken skeletal muscle cells express polypeptides that are antigenically related to alpha-spectrin (Mr 240,000) and beta-spectrin (Mr 220,000-225,000), the major components of the erythrocyte membrane- skeleton, and to ankyrin (Mr 237,000; also termed goblin in chicken erythrocytes), which binds spectrin to the transmembrane anion transporter in erythrocytes. Comparative immunoblotting of SDS- solubilized extracts of presumptive myoblasts and fully differentiated myotubes cultured in vitro demonstrated that there is a dramatic accumulation of ankyrin and alpha- and beta-spectrin during myogenesis and a concomitant switch in the subunit composition of spectrin from alpha gamma to alpha beta. Analysis of early time points in myogenesis (12-96 h) revealed that these changes occur shortly after the main burst of cell fusion. To determine the temporal relationship between cell fusion and the accumulation of ankyrin and alpha- and beta- spectrin, we treated presumptive myoblasts with 2 mM EGTA, which resulted in the complete inhibition of cell fusion. The incorporation of [35S]methionine into total protein and, specifically, into alpha-, gamma-, and beta-spectrin remained the same in EGTA-treated and control cells. Analysis by immunoblotting of the amounts of ankyrin and alpha- and beta-spectrin in fusion-blocked cells revealed that there was no effect on accumulation for the first 19 h. However, there was then a dramatic cessation in their accumulation, and thereafter, the amount of each protein at steady state remained constant. Upon release from the EGTA block, the cells fused rapidly (less than 11 h), and the accumulation of ankyrin and alpha- and beta-spectrin was reinitiated after a lag period of 3-5 h at a rate similar to that in control cells. The inhibition in the accumulation of newly synthesized ankyrin, alpha- spectrin, and beta-spectrin in EGTA-treated myoblasts was not characteristic of all structural proteins, since the accumulation of the muscle-specific intermediate filament protein desmin was the same in control and fusion-blocked cells. These results show that in myogenesis, the synthesis of ankyrin and alpha- and beta-spectrin and their accumulation as a complex, although concurrent, are not coupled events. We hypothesize that the extent of assembly of these components of the membrane-skeleton in muscle cells is determined by a control mechanism(s) operative at the posttranslational level that is triggered near the time of cell fusion and the onset of terminal differentiation

Avian lens spectrin: subunit composition compared with erythrocyte and brain spectrin

Chicken lens spectrin is composed predominantly of equimolar amounts of two polypeptides with solubility properties similar, but not identical, to erythrocyte spectrin. The larger polypeptide, Mr 240,000 (lens alpha- spectrin), co-migrates with erythrocyte and brain alpha-spectrin on one- and two-dimensional SDS polyacrylamide gels and cross-reacts with antibodies specific for chicken erythrocyte alpha-spectrin; the smaller polypeptide, Mr 235,000 (lens gamma-spectrin), co-migrates with brain gamma-spectrin and does not cross-react with either the alpha-spectrin antibodies specific for chicken erythrocyte beta-spectrin. Minor amounts of polypeptides antigenically related to erythrocyte beta- spectrin with a greater electrophoretic mobility than lens gamma- spectrin are also detected in lens. The equimolar ratio of lens alpha- and gamma-spectrin is invariantly maintained during the extraction of lens plasma membranes under different conditions, or after immunoprecipitation of whole extracts of lens with erythrocyte alpha- spectrin antibodies. Two-dimensional peptide mapping reveals that whereas alpha-spectrins from chicken erythrocytes, brain, and lens are highly homologous, the gamma-spectrins, although related, have some cell-type-specific peptides and are substantially different from erythrocyte beta-spectrin. Thus, the expression of cell-type-specific gamma- and beta-spectrins may be the basis for the assembly of a spectrin-plasma membrane complex whose molecular composition is tailored to the functional requirements of the particular cell-type

Assessments of kidney function and morphology of tramadol-diclofenac treated albino rats

Background: Tramadol-diclofenac (TD-DF) could be used in chronic pain management. Concurrent use may present renal complications due to their individual nephrotoxic profile. The present study assessed the kidney function and histology of tramadol-diclofenac treated albino rats.Methods: Forty two adult albino rats divided into seven groups A-G were used for this study. Rats were orally administered with TD (12 mg/kg/day), DF (6 mg/kg/day), and TD-DF for 14 days including two recovery groups. Rats were weighed and sacrificed at the termination of drug treatment. Serum was extracted from blood and evaluated for creatinine (Cr), urea (U), uric acid (UA), total protein (TP), albumin (Ab) and serum electrolytes (K+, Na+, Cl-, and HCO3-). Kidneys were excised weighed and evaluated for alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), superoxide dismutase (SOD), catalase (CAT) glutathione (GSH), glutathione peroxidase (GPX), malondialdehyde (MDA) levels and histological damage.Results: The body weight, absolute and relative kidney weights and serum electrolytes were not significantly (p> 0.05) altered in the TD-DF treated rats in comparison to control. However, the levels of Cr, U, UA, AST, ALT, ALP and MDA were significantly (p<0.05) increased whereas Ab, TP, SOD, GSH, GPX and CAT were significantly (p<0.05) decreased in the TD-DF treated rats in comparison to treatments with individual doses of TD and DF. Varying degrees of histological damage were observed in the kidneys of TD-DF treated rats. However, nephrotoxic effects due to treatment with TD-DF were reversed in the recovery groups.Conclusion: The use of tramadol-diclofenac could be associated with reversible nephrotoxicity; therefore renal function assessment is advised before tramadol-diclofenac use

Hepatotoxic Assessment of Tramadol-Diclofenac Use: A Study in a Rat Model

The concurrent use of tramadol and diclofenac may increase hepatotoxic risk due to their individual hepatotoxic effects. This study assessed the hepatotoxic effect of tramadol-diclofenac administration in albino rats. Twenty-four adult male albino rats (200-220g) randomized into four groups were orally administered with tramadol (12mg/kg/day), diclofenac (6mg/kg/day) and tramadol-diclofenac for 14 days respectively. The rats were anesthetized, blood samples were collected and evaluated for serum liver function and lipid parameters. Liver samples were weighed and evaluated for biochemical parameters and histology. The effects of tramadol-diclofenac on the body and liver weights did not differ significantly (p>0.05) when compared to control. Also, effects were not significant (p>0.05) on blood glucose, and serum cholesterol, triglyceride, low and high density lipoprotein cholesterol levels when compared to control. Liver and serum levels of aminotransferases, alkaline phosphatase, lactate dehydrogenase, gamma–glutamyl transferase, conjugated bilirubin and total bilirubin increased significantly in rats treated with tramadol (p<0.05), diclofenac (p<0.01) and tramadol-diclofenac (p<0.001) when compared to control. Furthermore, significant decreases in liver catalase, glutathione, superoxide dismutase, glutathione peroxidase levels with significant increases in malondialdehyde levels occurred in rats treated with tramadol (p<0.05), diclofenac (p<0.01) and tramadol-diclofenac (p<0.001) when compared to control. Hepatocyte necrosis was observed in rats treated with tramadol-diclofenac. Tramadol-diclofenac may increase hepatotoxic risk at doses used for this study

Effect of thermocycling on the tensile and shear bond strengths of three soft liners to a denture base resin

STATEMENT OF PROBLEM: In clinical practice, loss of adhesion between the silicone-based denture liner and the denture base resin is always an undesirable event that might cause loss of material softness, water sorption, bacterial colonization and functional failure of the prosthesis. PURPOSE: This study evaluated the effect of thermocycling on tensile and shear bond strengths of three soft liner materials to a denture base acrylic resin. MATERIAL AND METHODS: Three resilient liners (Mucopren-Soft, Mollosil-Plus and Dentusil) and a heat-polymerized acrylic resin (QC-20) were processed according to manufacturers' directions. Sixty specimens (14 x 14 mm cross-sectional area) per bond strength test (20 for each liner) were fabricated and either stored in water at 37ºC for 24 hours (control groups; n=10) or thermocycled 3,000 times in water between 5ºC and 55ºC (test groups; n=10). The specimens were tested in tensile and shear strength in a universal testing machine until fracture. Bond strength means were compared between water-stored and thermocycled groups for each material, as well as among materials for each treatment (water storage or thermocycling). Failure mode (adhesive, cohesive and mixed) after debonding was assessed. Data were analyzed statistically by paired Student's t-test and ANOVA at 5% significance level. RESULTS: The water-stored groups had statistically significant higher bond strengths than the thermocycled groups (

Health social organizations as a way of public/private management

O presente tem como objetivo analisar o processo de implementação das organizações sociais de saúde (OSS), no Estado de São Paulo, focalizando o papel desempenhado por fatores como autonomia administrativa e financeira, direcionamento proposto pelo contrato de gestão e o emprego de instrumentos e práticas gerenciais inovadoras, como fatores que condicionam o ganho de eficiência destas (OSS) frente às unidades da administração direta (AD). A abordagem adotada foi a do estudo comparativo, que propõe estabelecer possibilidades de, a partir da confrontação entre duas unidades (HOSS e HAD), identificar os elementos capazes de explicar esta diferença de desempenho entre os dois modelos de gestão. A investigação aponta para a influência positiva da autonomia administrativa e financeira, da direcionalidade imprimida aos processos de trabalho pelas metas estabelecidas no contrato de gestão e de tecnologias gerenciais inovadoras com uso intensivo da informação como base para a tomada de decisão. Este resultado, longe de indicar a completa conversão da AD para a publicização por meio do modelo OSS, aponta para as possibilidades e limites de desenvolvimento da AD, pela incorporação de tecnologias gerenciais implementadas no âmbito das OSS.This work has as objective to analyze the implementation process of the Health Social Organizations (OSS), in the State of São Paulo, focusing the role played by factors as administrative and financial autonomy, direction proposed by the Management Contract and the use of instruments and innovative management practices, as factors that give condition to the gain of efficiency of these OSS facing the Direct Administration units (AD). The adopted approach was the Comparative Study, which proposes the establishment of possibilities, from the confrontation between two units (HOSS and HAD), to identify the elements capable of explaining this difference of performance between the two models of management. The research points to the positive influence of the administrative and financial autonomy, to the direction given to the work processes by goals setting in the Management Contract and innovative management technologies with the intensive use of the information as base for taking decisions. This result, far from indicating the complete conversion of AD to the publicizing by the OSS model, points to the possibilities and limits of development of AD, by the incorporation of management technologies in the OSS environment

Fuel price transmission mechanisms in Portugal

This study aims to analyze the behavior of fuel prices at the pump (unleaded gasoline and diesel) in Portugal, relative to positive and negative variations in Brent Crude Oil prices. Applying an autoregressive distributed lags model (ARDL) to weekly time series data for the period of January 2004 through May 2009, we detected some signs of asymmetry in the transmission price mechanism. However, these patterns are not statistically significant enough to reject hypotheses of symmetry in the price adjustment mechanisms of fuels in Portugal.info:eu-repo/semantics/publishedVersio

Immunohistochemical studies of stellate cells in experimental cholestasis in newborn and adult rats

BACKGROUND AND AIMS: Although there is much known about liver diseases, some aspects remain unclear, such as the nature of the differences between the diseases observed in newborn infants and those in adults. For example, how do newborns respond to duct epithelial cell injury? Do the stellate cells in newborns respond similarly to those in adults during biliary obstruction? METHODS: Ninety newborn Wistar rats aged six days, weighing 8.0 - 13.9 g each, and 90 adult rats weighing 199.7 - 357.0 g each, were submitted to bile duct ligation. After surgery, they were randomly divided and sacrificed on the 3rd, 5th, 7th, 14th, 21st or 28th day post-bile duct ligation. Hepatic biopsies were obtained and immunohistochemical semi-quantification of desmin and &#945;-SMA expression was performed in hepatic stellate cells and in myofibroblasts in the portal space, and between the portal space and the liver lobule. RESULTS: Desmin expression in the myofibroblast cells post-bile duct ligation was higher in young rats, reaching its peak level in a shorter time when compared to the adult animals. The differences between the groups for &#945;-SMA expression were less significant than for desmin. CONCLUSIONS: These findings indicate that there is an increase in the number of collagen-producing myofibroblast cells in young animals, suggesting that there is more intense fibrosis in this population. This finding may explain why young animals with bile duct obstruction experience more intense portal fibrosis that is similar to the pathology observed in the livers of newborns with biliary atresia